1. Field of the Invention
The present invention relates to a heat pump air conditioning system comprising an additional heater and a method for operating the same, and more particularly to an air conditioning system comprising an additional heater driven during a standby time taken to simultaneously operate all of a plurality of compressors so as to rapidly satisfy an increased heating load, and a method for operating the air conditioning system.
2. Description of the Related Art
Hereinafter, a conventional air conditioning system comprising an additional heater and a method for operating the system will be described with reference to FIGS. 1 and 2.
FIG. 1 is a block diagram illustrating a heating cycle of a general air conditioning system, and FIG. 2 is a flow chart illustrating a method for operating a conventional air conditioning system comprising an additional heater.
A recent air conditioner having cooling and heating functions comprises a compressor, a condenser, an expansion valve, and an evaporator. A thermal cycle is formed by a refrigerant passing through the compressor, the condenser, the expansion valve, and the evaporator. Herein, the thermal cycle is divided into a cooling cycle for discharging cold air in a cooling mode and a heating cycle for discharging warm air in a heating mode by converting a flow direction of the refrigerant. Thereby, the air conditioner serves to condition air of a room. The aforementioned air conditioner having cooling and heating functions is referred to as a heat pump air conditioner.
Such a heat pump air conditioner uses a four-way valve for selecting the flow direction of the refrigerant installed in a conventional cooling apparatus, thereby reversing functions of components of the cooling apparatus so as to convert the cooling cycle into the heating cycle in which warm air is discharged from an indoor, unit and cold air is discharged from an outdoor unit.
The conventional air conditioning system is operated in the heating mode via the heating cycle as shown in FIG. 1, as follows.
A plurality of compressors 10 for converting a refrigerant from a low-temperature and low-pressure state into a high-temperature and high-pressure state includes a first compressor 11 and a second compressor 12. The first and second compressors 11 and 12 are simultaneously operated, or the first compressor 11 is operated and the second compressor 12 is stopped, thereby variably changing the compression capacity of the refrigerant.
The four-way valve 20 transmits the refrigerant discharged from the plural compressors 10 to an outdoor heat exchanger 50 in the cooling mode and to an indoor heat exchanger 30 in the heating mode, thereby alternating the flow direction of the refrigerant.
The indoor heat exchanger 30 serves as condensing means for condensing the gaseous refrigerant in the high-temperature and high-pressure state into a liquid refrigerant. An indoor unit 39 comprises the indoor heat exchanger 30, and an indoor blower (not shown) installed next to the indoor heat exchanger 30 so as to discharge warm or cold air to the interior of a room. The indoor blower includes a motor 31 and an indoor fan 32.
The expansion valve 40 expands the liquid refrigerant condensed by the condensing means into a two-phase refrigerant of solid and liquid phases in a low-temperature and low-pressure state.
The outdoor heat exchanger 50 serves as evaporating means for converting the two-phase refrigerant into a gaseous refrigerant by absorbing external heat. An outdoor unit 99 comprises the outdoor heat exchanger 50, and an outdoor blower (not shown) installed next to the outdoor heat exchanger 50 so as to discharge air to the outdoor heat exchanger 50 and increase heat exchange efficiency. The outdoor blower includes an outdoor fan (not shown) and a motor (not shown).
Thereby, a heating cycle consisting of compression, condensation, expansion, and evaporation is formed.
When the above-described air conditioning system is operated in the heating mode, in order to effectively heat a room, the heat exchange between the outdoor heat exchanger 50 and external cold air contacting the outdoor heat exchanger 50 must be effectively achieved. A temperature difference between the external air and the refrigerant passing through the outdoor heat exchanger 50 is very low. Therefore, other heating means such as a stove, a boiler, a heater, etc. are additionally used to heat the interior of the room in a cold area, thereby causing a heavy economic burden to customers.
Further, when the external cold air contacts the outdoor heat exchanger 50, frost forms on the surface of the outdoor heat exchanger 50, the interior of which has a comparatively high temperature, thereby hindering the circulation of the refrigerant and reducing the efficiency of the compressor. Therefore, the conventional air conditioner having an insufficient heating function is limitedly used in summer time, thereby causing an inconvenience to users.
With reference to FIG. 2, the method for operating the aforementioned conventional air conditioner is described as follows.
At the early stage of operation, a plurality of the compressors are simultaneously operated so as to have a compression capacity of the refrigerant of 100%. (S1)
A control unit (not shown) for entirely controlling the air conditioner system senses the variation of a heating load within a room, and then judges whether the heading load is increased or not. (S2)
When the heating load is increased, all of the plural compressors are simultaneously operated so that the compression capacity of the refrigerant is 100%, and when the heating load is decreased, the first compressor is continuously operated but the second compressor is stopped so that the compression capacity of the refrigerant is 40% via the heating cycle. (S3)
In case room temperature is lowered according to the operation of only the first compressor or a user sets a higher desirable room temperature, the heating load is increased. Then, the control unit judges whether the heating load is increased or not. (S4)
When the heating load is not increased, only the first compressor is continuously operated. On the other hand, when the heating load is increased, the control unit outputs a signal for re-operating the stopped second compressor to the second compressor, and simultaneously judges whether a standby time for re-operating the stopped compressor has passed or not. (S5) Hereinafter, the signal is referred to as a full activation signal, and the standby time is referred to as a full activation standby time.
The full activation standby time denotes a time taken from the beginning of the re-operation of the stopped second compressor to the complete re-operation of the stopped second compressor in order to simultaneously operate all of the plural compressors so that the compression capacity of the refrigerant becomes 100%.
Therefore, during the full activation standby time, the control unit continuously maintains the operation of the first compressor so that the compression capacity of the refrigerant is 40%. (S6) After a lapse of the full activation standby time, the control unit operates all of the plural compressors simultaneously so that the compression capacity of the refrigerant is 100%.
However, since the above-described conventional air conditioner does not satisfy the increased heating load during the full activation standby time, the room temperature is rapidly lowered, thereby causing discomfort and inconvenience to users.
Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a heat pump air conditioning system comprising an additional heater and a method for operating the same, in which the additional heater is automatically driven without a user""s manual manipulation during a full activation standby time taken to simultaneously operate all of a plurality of compressors so as to rapidly satisfy an increased heating load, thereby providing convenience to users, and preventing the lowering of room temperature so as to improve users"" comfort.
In accordance with one aspect of the present invention, the above and other objects can be accomplished by the provision of a heat pump air conditioning system with an additional heater, comprising:
an air conditioner for conditioning air of a room so as to satisfy a heating load by circulating a refrigerant via a heating cycle consisting of compression, condensation, expansion, and evaporation;
an additional heater installed within the air conditioner and driven so as to rapidly satisfy the heating load; and
a control unit for controlling a compression capacity of the refrigerant according to the heating load and controlling an operation of the additional heater.
In accordance with another aspect of the present invention, there is provided a method for operating a heat pump air conditioning system with an additional heater, comprising:
the first step of selectively operating a plurality of compressors;
the second step of sensing an increase of a heating load exceeding a total capacity of the compressors selectively operated in the first step;
the third step of inputting a full activation order into the system for instructing all of the plural compressors to operate, and simultaneously the additional heater to drive; and
the fourth step of stopping the operation of the additional heater and simultaneously operating all of the plural compressors.